3D Airborne EM Forward Modelling by the Spectral-Element Method for Deformed Hexahedral Meshes

Abstract

Summary Accuracy and efficiency of forward modelling is important for successful and practical inversion and interpretation of airborne EM data. Finite-difference and finite-element methods are currently the most common methods used. However, an alternative approach is the spectral-element (SE) method, which is attractive because of its flexibility and potential for high accuracy. The SE method has previously been implemented for airborne EM modeling using regular hexahedral meshes. Here, we implement the SE method for deformed hexahedral meshes. This enables complex geological bodies to be modelled. A shape function is used to calculate the Jacobian matrix of the mapping between the physical mesh coordinates and the reference coordinates for the SE method. We apply our SE method to the computation of frequency-domain airborne EM responses. Through some numerical examples with rough mesh subdivision and simple mesh deformation, we demonstrate the flexibility and accuracy of the SE method for computing frequency-domain airborne EM responses, —thus verifying the potential of SE method for modeling complex geological bodies.